It’s not apocryphal. My father worked for the US Navy making training and orientation films; one of these was about firefighting and hazardous materials handling on board ship. It included some entertaining segments — for some reason they use (or used, this was the 80s) pure sodium on some ships and they described the difficulty and danger of storing such a substance. The use of a broom to detect invisible but very dangerous leaks from high-pressure steam lines was also demonstrated.